There are myriad types of buckles that have been used for many purposes. Buckles are often used to releasably fasten together straps. For example, helmet designs often include buckles for the chinstrap that provide the user with means of fastening and releasing the chinstrap to facilitate use of the helmet.
Helmet chinstrap buckles have taken a variety of forms. Some use two "D" shaped elements through which one strap is threaded to adjustably fasten together the two portions of the chinstrap. Other buckles include two or more buckle elements that mate in any number of fashions in an engaged state and are releasable through some means on one or more of the buckle elements. One such buckle includes an engaging member with a protruding operating section that can be inadvertently caught, prematurely releasing the buckle.
These buckles are frequently relatively complex mechanisms that are difficult to engage and sometimes difficult to release. These problems have caused many chinstrap buckles to perform poorly on helmets. Paratroopers in particular require a buckle that is easily releasable by the user, while not being easily inadvertently released; such a buckle would inhibit accidental release while still allowing the paratrooper to release the buckle in an emergency situation such as when the helmet gets caught during a jump.
For any combat soldier, it is important that the helmet chinstrap buckle be operable while the user is wearing gloves or mittens. This is important or essential when the soldiers are in extreme cold or operating under a chemical environment. Further, the metal buckle parts of many helmet chinstraps can act as secondary missiles that are capable of injuring the wearer.